Bogs down at 4500

[drmaxdc]

Just rebuilt carbs on my 83 GS850L alls fine except it bogs at 4500 for a bit. Carbs done right. Any thoughts? Thanks

[Dave8338]

What are you running for an air filter(s)?

Sounds like it is happening right off the transition from pilot to main.
O-rings on the head changed out? Any cracks in the intake boots?
Everything sealed tightly?

[drmaxdc]

All new rubbers and stock intake

[Dave8338]

Can I assume that when you put the new intake tubes on, you also did the intake o-rings?

Otherwise, If you are running the stock filter (foam) you can try adding a little more oil to it.

If that doesn't seem to make a difference, try shimming the jet needles up 1/2 -1 notch up.

[drmaxdc]

It does have new o-rings. I just was wondering if there were any adjustment I could make that would make a difference. What would make it run different now after a carb rebuild?

[BassCliff]

Hi,

Carb tuning is a fine art. I wish I knew it better.

As Mr. Dave8338 suggests, shimming the needles may smooth the transition.

Did you use carb rebuild kits? Did you replace any jets using those kits? Aftermarket carb rebuild kits have a reputation of being less than OEM quality.

If not, did you carefully check to see if any jets or needles were worn? Have a look see here:

Fine Points Of CV Carb Internals
Shimming The Needle

Thank you for your indulgence,

BassCliff

[drmaxdc]

Needles and jets looked good. I did replace two of them with the kit ones. Would adjusting the air screws out more make a difference?

[Ohioan]

On those carbs, they're fuel screws, not air screws. Turning them out would make the bike run richer at idle, not at 1/4-1/2 throttle.

take a look at this website for more information http://www.iwt.com.au/mikunicarb.htm The trouble shooting section was helpful to me.

The best way to know exactly what the problem is would be to do "plug chops". You need to know where the throttle position is when it's running rough to know what needs adjustment.

I had a similar issue at 1/4 throttle. I found that I was really lean on all four cylinders. I raised the needles a notch last night, but didn't get a chance to check it out.